Philips Semiconductors Letter Symbols - Diodes General LETTER SYMBOLS amb ambient The letter symbols for diodes detailed in this section are based on IEC publication number 747. (AV), (av) average value (BR) breakdown (CL) clamping d diode diff differential F, f forward, fall I, i input The following is a list of basic letter symbols used with semiconductor diodes: j junction j-a junction to ambient C capacitance j-tp junction to tie-point E, e energy K knee f frequency L load I, i current M, m peak or crest value L inductance max maximum P, p power min minimum Q charge nom nominal R, r resistance O, o output S temperature coefficient on turn-on T temperature P, p pulse t time R, r V, v voltage as first subscript: reverse, rise. as second subscript: repetitive, recovery. Z impedance. ref reference Basic letters In the representation of currents, voltages and powers, upper-case letter symbols are used to indicate all values except instantaneous values that vary with time; these are represented by lower-case letters. (RMS), (rms) root-mean-square value Subscripts S, s As first subscript: storage, series, switching. As second subscript: surge (non-repetitive). • Continuous (DC) values (without signal), e.g. IF stg storage • Instantaneous total values, e.g. iRR th thermal • Average total values, e.g. IF(AV) tot total • Peak total values, e.g. VRSM tp tie-point • Root-mean-square total values, e.g. IF(RMS). W working Lower-case subscripts are used for the indication of values applying to the varying component alone: Z, z regulator, working (zener). Upper-case subscripts are used for the indication of: • Instantaneous values, e.g. trr • Root-mean-square values, e.g. If(rms) • Peak values, e.g. Vfm • Average values, e.g. If(av). If more than one subscript is used, the subscript for which both styles exist are either all upper-case or all lower-case. The following is a list of subscripts used with basic letter symbols for semiconductor diodes: 1999 May 07 1